diff --git a/src/pages/activity-outline/index.vue b/src/pages/activity-outline/index.vue
index cfef6e8..56b7fa6 100644
--- a/src/pages/activity-outline/index.vue
+++ b/src/pages/activity-outline/index.vue
@@ -158,8 +158,10 @@
 <script>
 	import {
 		activityOutlineGen,
+		attachHeartbeat,
 		buildWebSocketUrl,
-		getCurrentUser
+		getCurrentUser,
+		streamActivityOutlineGen
 	} from './service'
 	import {
 		isFailedPayload,
@@ -195,6 +197,7 @@
 				activeMessageId: '',
 				socketTask: null,
 				socketConnectPromise: null,
+				socketHeartbeatStop: null,
 				streamStarted: false,
 				streamFailed: false,
 				streamResolver: null,
@@ -364,6 +367,10 @@
 				})
 			},
 			disconnectWebSocket() {
+				if (this.socketHeartbeatStop) {
+					this.socketHeartbeatStop()
+					this.socketHeartbeatStop = null
+				}
 				this.socketConnectPromise = null
 				const socketTask = this.socketTask
 				this.socketTask = null
@@ -471,6 +478,10 @@
 						}
 					}
 
+					socketTask.onOpen(() => {
+						// 握手成功后再挂心跳：连接没建起来时发出去只会失败
+						this.socketHeartbeatStop = attachHeartbeat(socketTask)
+					})
 					socketTask.onMessage((event) => {
 						const raw = String((event && event.data) || '')
 						if (raw === SOCKET_CONNECTED_TEXT) {
@@ -539,23 +550,21 @@
 				}
 				this.loading = true
 				this.clearResult()
-				this.resultSummary = '正在建立 WebSocket 连接...'
+				this.resultSummary = '正在提交生成任务...'
 				try {
-					await this.connectWebSocket()
-					this.resultSummary = '连接成功，已提交生成任务，等待流式返回...'
+					// 一律走 HTTP 流式（/stream），不再先连 WebSocket：
+					// 触发生成的那个 POST 在整段生成期间是零字节的，会被链路上的
+					// 60s 空闲超时掐成 504 Gateway Time-out。/stream 每 15s 有后端
+					// 心跳续命，帧内容与 WS 完全一致。
+					const payload = this.buildPayload()
+					this.resultSummary = '已提交生成任务，等待流式返回...'
 					const waitStream = this.createStreamWaiter()
-					const data = await activityOutlineGen(this.buildPayload())
-					this.result = data || null
-					if (!this.streamStarted && data && this.parseOutline(data)) {
-						this.outlineMarkdown = this.parseOutline(data)
-						this.syncEditableOutline()
-						this.resultSummary = this.buildSummary() || '接口直接返回生成结果'
-						this.loading = false
-						this.resolveStream()
-						this.disconnectWebSocket()
-					} else {
-						await waitStream
-					}
+					await streamActivityOutlineGen(payload, {
+						onMessage: (raw) => this.handleSocketMessage(raw)
+					}).promise
+					// 兜底：流结束但没收到 __END__ 时也别把页面卡在加载中
+					this.resolveStream()
+					await waitStream
 					if (this.streamFailed) {
 						// 后端判定工作流失败，正文区已显示失败文案，这里同步提示
 						this.showToast('生成失败，请稍后重试')
diff --git a/src/pages/activity-outline/service.js b/src/pages/activity-outline/service.js
index 829caf5..b8886f3 100644
--- a/src/pages/activity-outline/service.js
+++ b/src/pages/activity-outline/service.js
@@ -1,11 +1,13 @@
 import {
 	API_BASE_URL,
 	apiRequest,
+	attachHeartbeat,
 	buildWebSocketUrl,
-	getCurrentUser
+	getCurrentUser,
+	streamActivityOutlineGen
 } from '../assistant/chat-service'
 
-export { buildWebSocketUrl, getCurrentUser }
+export { attachHeartbeat, buildWebSocketUrl, getCurrentUser, streamActivityOutlineGen }
 
 export function activityOutlineGen(data) {
 	return apiRequest({
diff --git a/src/pages/assistant/chat-service.js b/src/pages/assistant/chat-service.js
index 5f5e95f..e92bcf6 100644
--- a/src/pages/assistant/chat-service.js
+++ b/src/pages/assistant/chat-service.js
@@ -486,14 +486,219 @@ export function uploadAiFile(file, app) {
 	})
 }
 
-export function buildWebSocketUrl(userId) {
-	const url = String(API_BASE_URL || '')
-	if (/^https?:\/\//.test(url)) {
-		return `${url
-			.replace(/^https:/, 'wss:')
-			.replace(/^http:/, 'ws:')
-			.replace(/\/api\/?$/, '')
-			.replace(/\/$/, '')}/chat/${userId}`
+// WebSocket 的地址拼接与心跳统一在 utils/chat-socket.js，
+// 这里继续转发，三个页面的 import 不用动
+export { buildWebSocketUrl, attachHeartbeat } from '../../utils/chat-socket'
+
+// ---------------------------------------------------------------------------
+// HTTP 流式（SSE）通道：WebSocket 握手被网关挡掉时的退路
+//
+// 生产网关在 /api 前面丢 Upgrade 头，wss 建不起来（网关侧不让改）。后端因此
+// 把每条 AI 链路都开了一份 /stream 端点：请求体与原接口一字不差，响应是
+// text/event-stream，每个 data: 行就是原来 WebSocket 上的一帧（同一段 JSON）。
+// 端上先试 WebSocket，连不上就落到这里，页面处理逻辑完全复用 handleSocketMessage。
+// ---------------------------------------------------------------------------
+
+/** 把字节流切成字符串，并返回「还没凑齐的多字节尾部」留给下一块。 */
+function decodeUtf8Chunk(bytes) {
+	let text = ''
+	let index = 0
+	while (index < bytes.length) {
+		const first = bytes[index]
+		if (first < 0x80) {
+			text += String.fromCharCode(first)
+			index += 1
+			continue
+		}
+		let extra = 0
+		if ((first & 0xe0) === 0xc0) {
+			extra = 1
+		} else if ((first & 0xf0) === 0xe0) {
+			extra = 2
+		} else if ((first & 0xf8) === 0xf0) {
+			extra = 3
+		} else {
+			// 非法首字节，跳过，避免整条流卡死
+			index += 1
+			continue
+		}
+		if (index + extra >= bytes.length) {
+			// 中文字符被切在两块之间：整段留给下一次拼
+			break
+		}
+		let codePoint = first & (0x3f >> extra)
+		for (let step = 1; step <= extra; step += 1) {
+			codePoint = (codePoint << 6) | (bytes[index + step] & 0x3f)
+		}
+		text += String.fromCodePoint(codePoint)
+		index += extra + 1
 	}
-	return `${url.replace(/\/api\/?$/, '')}/chat/${userId}`
+	return { text, consumed: index }
+}
+
+/**
+ * 发一条流式请求，把每个 SSE 帧原样交给 onMessage。
+ *
+ * @param {object} options
+ * @param {string} options.url 后端 `/stream` 端点
+ * @param {object} options.data 与普通接口相同的请求体
+ * @param {(raw: string) => void} options.onMessage 每帧回调，内容与 WebSocket 帧一致
+ * @param {() => void} [options.onDone] 流正常结束
+ * @param {(error: Error) => void} [options.onError] 流异常结束
+ * @returns {{ abort: () => void, promise: Promise<void> }}
+ */
+export function streamAiRequest({ url, data, onMessage, onDone, onError, timeout = AI_REQUEST_TIMEOUT }) {
+	const requestData = data ? { ...data } : {}
+	requestData.tenantId = DEFAULT_TENANT_ID
+	addSignature(requestData)
+
+	const token = getToken()
+	const header = { 'Content-Type': 'application/json' }
+	if (token) {
+		header[TOKEN_HEADER_NAME] = token
+	}
+
+	let pending = new Uint8Array(0)
+	let textBuffer = ''
+	let settled = false
+	let abortHandle = () => undefined
+
+	const finish = (error) => {
+		if (settled) {
+			return
+		}
+		settled = true
+		if (error) {
+			onError && onError(error)
+			return
+		}
+		onDone && onDone()
+	}
+
+	const drainFrames = () => {
+		let boundary = textBuffer.indexOf('\n\n')
+		while (boundary !== -1) {
+			const frame = textBuffer.slice(0, boundary)
+			textBuffer = textBuffer.slice(boundary + 2)
+			boundary = textBuffer.indexOf('\n\n')
+			if (frame.startsWith(':')) {
+				// SSE 注释行（后端用它把响应头先顶出去）
+				continue
+			}
+			const payload = frame
+				.split('\n')
+				.filter((line) => line.indexOf('data:') === 0)
+				.map((line) => line.slice(5).replace(/^ /, ''))
+				.join('')
+			if (payload && onMessage) {
+				onMessage(payload)
+			}
+		}
+	}
+
+	const handleBytes = (arrayBuffer) => {
+		const incoming = new Uint8Array(arrayBuffer)
+		const merged = new Uint8Array(pending.length + incoming.length)
+		merged.set(pending, 0)
+		merged.set(incoming, pending.length)
+		const decoded = decodeUtf8Chunk(merged)
+		pending = merged.slice(decoded.consumed)
+		if (decoded.text) {
+			textBuffer += decoded.text
+			drainFrames()
+		}
+	}
+
+	const promise = new Promise((resolve, reject) => {
+		const fail = (error) => {
+			finish(error)
+			reject(error)
+		}
+
+		// #ifdef H5
+		const controller = typeof AbortController === 'function' ? new AbortController() : null
+		abortHandle = () => controller && controller.abort()
+		fetch(url, {
+			method: 'POST',
+			headers: header,
+			body: JSON.stringify(requestData),
+			signal: controller ? controller.signal : undefined
+		})
+			.then((response) => {
+				if (!response.ok) {
+					throw new Error(`流式请求失败（HTTP ${response.status}）`)
+				}
+				if (!response.body || typeof response.body.getReader !== 'function') {
+					throw new Error('当前环境不支持流式读取')
+				}
+				const reader = response.body.getReader()
+				const pump = () =>
+					reader.read().then(({ done, value }) => {
+						if (done) {
+							finish()
+							resolve()
+							return
+						}
+						handleBytes(value)
+						return pump()
+					})
+				return pump()
+			})
+			.catch(fail)
+		// #endif
+
+		// #ifndef H5
+		const task = uni.request({
+			url,
+			method: 'POST',
+			data: requestData,
+			header,
+			enableChunked: true,
+			timeout,
+			responseType: 'arraybuffer',
+			success: () => {
+				// 分块模式下 success 只在流结束时触发，正常完成以这里为准
+				finish()
+				resolve()
+			},
+			fail: (error) => {
+				fail(new Error((error && (error.errMsg || error.message)) || '流式请求失败'))
+			}
+		})
+		if (task && typeof task.onChunkReceived === 'function') {
+			task.onChunkReceived((chunk) => handleBytes(chunk.data))
+			abortHandle = () => task.abort && task.abort()
+		} else {
+			// 老基础库没有分块能力：直接报错，让页面提示升级微信
+			fail(new Error('当前微信版本不支持流式请求，请升级微信后重试'))
+		}
+		// #endif
+	})
+
+	return { abort: () => abortHandle(), promise }
+}
+
+/** 对话（HTTP 流式） */
+export function streamChatMessage(data, handlers) {
+	return streamAiRequest({ url: `${API_BASE_URL}/ai/chat/message/stream`, data, ...handlers })
+}
+
+/** 稿件生成（HTTP 流式） */
+export function streamManuscriptGen(data, handlers) {
+	return streamAiRequest({ url: `${API_BASE_URL}/ai/manuscriptGen/stream`, data, ...handlers })
+}
+
+/** 创意助手（HTTP 流式） */
+export function streamCreativeAssistant(data, handlers) {
+	return streamAiRequest({ url: `${API_BASE_URL}/ai/creativeAssistant/stream`, data, ...handlers })
+}
+
+/** 活动策划大纲（HTTP 流式） */
+export function streamActivityOutlineGen(data, handlers) {
+	return streamAiRequest({ url: `${API_BASE_URL}/ai/activityOutlineGen/stream`, data, ...handlers })
+}
+
+/** 智能文档处理（HTTP 流式） */
+export function streamDocumentProcess(data, handlers) {
+	return streamAiRequest({ url: `${API_BASE_URL}/ai/documentProcess/stream`, data, ...handlers })
 }
diff --git a/src/pages/assistant/index.vue b/src/pages/assistant/index.vue
index 7a51a64..fafe8e0 100644
--- a/src/pages/assistant/index.vue
+++ b/src/pages/assistant/index.vue
@@ -303,13 +303,15 @@
 <script>
 	import dayjs from '../../uni_modules/uv-ui-tools/libs/util/dayjs.js'
 	import {
+		attachHeartbeat,
 		buildWebSocketUrl,
-		creativeAssistant,
+		streamCreativeAssistant,
 		listAiChatHistory,
 		listAiChatList,
-		manuscriptGen,
+		streamManuscriptGen,
 		removeAiChatList,
 		sendMessage as sendChatMessage,
+		streamChatMessage,
 	} from './chat-service'
 	import {
 		WRITING_DOC_TYPE_FREE,
@@ -387,6 +389,7 @@
 				},
 				socketTask: null,
 				socketConnectPromise: null,
+				socketHeartbeatStop: null,
 				initialized: false
 			}
 		},
@@ -820,6 +823,10 @@
 				this.syncActiveChat()
 			},
 			disconnectWebSocket() {
+				if (this.socketHeartbeatStop) {
+					this.socketHeartbeatStop()
+					this.socketHeartbeatStop = null
+				}
 				this.socketConnectPromise = null
 				this.wsConnected = false
 				const socketTask = this.socketTask
@@ -887,6 +894,8 @@
 
 					socketTask.onOpen(() => {
 						this.wsConnected = false
+						// 握手成功后再挂心跳：连接没建起来时发出去只会失败
+						this.socketHeartbeatStop = attachHeartbeat(socketTask)
 					})
 					socketTask.onMessage((event) => {
 						const raw = String((event && event.data) || '')
@@ -1278,13 +1287,78 @@
 					}
 				}
 				if (this.activeChatMode === 'writing') {
-					const result = await manuscriptGen(this.buildWritingPayload(query))
-					setResult(this.formatWritingResult(result))
+					// 稿件生成同样要挂几十秒到一两分钟，普通 POST 期间链路上零字节，
+					// 会被 60s 空闲超时掐成 504。走 /stream 后后端每 15s 发心跳续命，
+					// 正文边推边显示，结构化的最终结果（标题等）放在末帧里。
+					let finalPayload = null
+					await streamManuscriptGen(this.buildWritingPayload(query), {
+						onMessage: (raw) => {
+							let frame = null
+							try {
+								frame = JSON.parse(raw)
+							} catch (error) {
+								return
+							}
+							if (!frame) {
+								return
+							}
+							if (frame.type === 'final') {
+								finalPayload = frame.result
+								return
+							}
+							if (frame.answer === '__END__') {
+								return
+							}
+							const chunk = frame.notice || frame.answer
+							if (chunk && target) {
+								const base = target.content === ASSISTANT_PENDING_TEXT ? '' : target.content
+								target.content = base + chunk
+							}
+						}
+					}).promise
+					if (finalPayload && Number(finalPayload.code) === 0) {
+						setResult(this.formatWritingResult(finalPayload.data))
+						return
+					}
+					if (finalPayload) {
+						setResult(finalPayload.message || FAILED_TEXT)
+						return
+					}
+					// 流断了但已经收到正文：保留已生成的部分，不要把整块覆盖成错误文案
+					if (target && target.content && target.content !== ASSISTANT_PENDING_TEXT) {
+						setResult(target.content)
+						return
+					}
+					setResult('生成超时了，请稍后重试。')
 					return
 				}
 				if (this.activeChatMode === 'image') {
-					const result = await creativeAssistant(this.buildImagePayload(query))
-					setResult(this.formatCreativeResult(result))
+					// 出图要一两分钟，这期间后端一个字节都不会推。普通 POST 在这段时间里
+					// 链路上完全空闲，会在 58s 左右被网关掐成 504（实测），所以改走 /stream：
+					// 后端每 15s 发一帧心跳续命，结果放在末帧 {type:'final', result} 里。
+					let finalPayload = null
+					await streamCreativeAssistant(this.buildImagePayload(query), {
+						onMessage: (raw) => {
+							let frame = null
+							try {
+								frame = JSON.parse(raw)
+							} catch (error) {
+								return
+							}
+							if (frame && frame.type === 'final') {
+								finalPayload = frame.result
+							}
+						}
+					}).promise
+					if (!finalPayload) {
+						setResult('出图超时了，请稍后重试。')
+						return
+					}
+					if (Number(finalPayload.code) !== 0) {
+						setResult(finalPayload.message || FAILED_TEXT)
+						return
+					}
+					setResult(this.formatCreativeResult(finalPayload.data))
 				}
 			},
 			openHistoryPanel() {
@@ -1384,11 +1458,23 @@
 					this.draft = ''
 					this.scrollToBottom()
 					if (this.activeChatMode === 'chat') {
-						await this.connectWebSocket()
-						await sendChatMessage({
+						// 先试 WebSocket。生产网关在 /api 前面把 Upgrade 头丢了，握手必然失败；
+						// 连不上就落到后端的 /stream 端点，帧内容与 WS 完全一致，
+						// 所以解析逻辑仍然复用 handleSocketMessage。
+						const viaSocket = await this.connectWebSocket()
+							.then(() => true)
+							.catch(() => false)
+						const payload = {
 							query,
 							conversationId: this.activeConversationId || undefined
-						})
+						}
+						if (viaSocket) {
+							await sendChatMessage(payload)
+							return
+						}
+						await streamChatMessage(payload, {
+							onMessage: (raw) => this.handleSocketMessage(raw)
+						}).promise
 						return
 					}
 					await this.sendModeMessage(query, assistantId)
diff --git a/src/pages/manuscript/index.vue b/src/pages/manuscript/index.vue
index 60bd98c..ab86727 100644
--- a/src/pages/manuscript/index.vue
+++ b/src/pages/manuscript/index.vue
@@ -212,9 +212,11 @@
 
 <script>
 	import {
+		attachHeartbeat,
 		buildWebSocketUrl,
 		getCurrentUser,
 		manuscriptGen,
+		streamManuscriptGen,
 		uploadTempFile
 	} from './service'
 	import {
@@ -261,6 +263,7 @@
 				activeConversationId: '',
 				socketTask: null,
 				socketConnectPromise: null,
+				socketHeartbeatStop: null,
 				streamStarted: false,
 				streamFailed: false,
 				streamResolver: null,
@@ -521,6 +524,10 @@
 				})
 			},
 			disconnectWebSocket() {
+				if (this.socketHeartbeatStop) {
+					this.socketHeartbeatStop()
+					this.socketHeartbeatStop = null
+				}
 				this.socketConnectPromise = null
 				this.wsConnected = false
 				const socketTask = this.socketTask
@@ -621,6 +628,8 @@
 
 					socketTask.onOpen(() => {
 						this.wsConnected = false
+						// 握手成功后再挂心跳：连接没建起来时发出去只会失败
+						this.socketHeartbeatStop = attachHeartbeat(socketTask)
 					})
 					socketTask.onMessage((event) => {
 						const raw = String((event && event.data) || '')
@@ -784,25 +793,23 @@
 				this.loading = true
 				this.clearGenerated()
 				this.generatedTitle = String(this.form.theme || '').trim()
-				this.responseSummary = '正在建立 WebSocket 连接...'
+				this.responseSummary = '正在提交生成任务...'
 				try {
-					await this.connectWebSocket()
+					// 一律走 HTTP 流式（/stream），不再先连 WebSocket：
+					// 触发生成的那个 POST 在整段生成期间是零字节的，会被链路上的
+					// 60s 空闲超时掐成 504 Gateway Time-out（自由创作、不选文体时最先撞上）。
+					// /stream 每 15s 有后端心跳续命，帧内容与 WS 完全一致。
+					const payload = this.buildPayload()
 					this.responseSummary = this.freeMode
 						? '自由创作已提交给 AI 创意助手，生成完成后一次性返回...'
-						: '连接成功，已提交生成任务，等待流式返回...'
+						: '已提交生成任务，等待流式返回...'
 					const waitStream = this.createStreamWaiter()
-					const result = await manuscriptGen(this.buildPayload())
-					if (!this.streamStarted && this.shouldTreatAsDirectResult(result)) {
-						this.applyParsedResult(
-							typeof result === 'string' ? this.parseSerializedResult(result) : result,
-							'接口直接返回生成结果'
-						)
-						this.loading = false
-						this.resolveStream()
-						this.disconnectWebSocket()
-					} else {
-						await waitStream
-					}
+					await streamManuscriptGen(payload, {
+						onMessage: (raw) => this.handleStreamFrame(raw)
+					}).promise
+					// 兜底：流结束但没收到 __END__ 时也别把页面卡在加载中
+					this.resolveStream()
+					await waitStream
 					if (this.streamFailed) {
 						// 后端判定工作流失败，正文区已显示失败文案，这里同步提示
 						this.showToast('生成失败，请稍后重试')
@@ -816,6 +823,34 @@
 					this.showToast((error && error.message) || '内容生成失败')
 				}
 			},
+			/**
+			 * SSE 帧分发：末帧带着接口的返回值（自由创作模式整段都不推正文，只能靠它），
+			 * 其余帧与 WebSocket 完全一致，继续交给 handleSocketMessage。
+			 */
+			handleStreamFrame(raw) {
+				let frame = null
+				try {
+					frame = JSON.parse(raw)
+				} catch (error) {
+					this.handleSocketMessage(raw)
+					return
+				}
+				if (!frame || frame.type !== 'final') {
+					this.handleSocketMessage(raw)
+					return
+				}
+				const result = frame.result
+				if (result && Number(result.code) === 0 && result.data) {
+					this.applyParsedResult(
+						typeof result.data === 'string' ? this.parseSerializedResult(result.data) : result.data,
+						'接口直接返回生成结果'
+					)
+					return
+				}
+				if (result && result.message) {
+					this.showToast(result.message)
+				}
+			},
 			copyGenerated() {
 				if (!this.markdownContent) {
 					this.showToast('暂无可复制的正文内容')
diff --git a/src/pages/manuscript/service.js b/src/pages/manuscript/service.js
index a4d0969..b01a3f8 100644
--- a/src/pages/manuscript/service.js
+++ b/src/pages/manuscript/service.js
@@ -1,12 +1,14 @@
 import {
 	API_BASE_URL,
 	apiRequest,
+	attachHeartbeat,
 	buildWebSocketUrl,
 	getCurrentUser,
-	getToken
+	getToken,
+	streamManuscriptGen
 } from '../assistant/chat-service'
 
-export { buildWebSocketUrl, getCurrentUser }
+export { attachHeartbeat, buildWebSocketUrl, getCurrentUser, streamManuscriptGen }
 
 export function manuscriptGen(data) {
 	return apiRequest({
diff --git a/src/utils/chat-socket.js b/src/utils/chat-socket.js
new file mode 100644
index 0000000..552661a
--- /dev/null
+++ b/src/utils/chat-socket.js
@@ -0,0 +1,64 @@
+import { API_BASE_URL } from './request'
+
+/**
+ * 端与后端 WebSocket 的连接细节，集中在这里。
+ *
+ * 三条链路（创意助手 / 稿件生成 / 活动策划大纲）此前各自散落着一份一模一样的
+ * 「拼 URL + 连 + 断」，改一次路径要改三处；现在统一走这里。
+ */
+
+/** 心跳间隔。nginx 的 proxy_read_timeout / 网关空闲超时普遍在 60s 上下，25s 留够余量。 */
+const HEARTBEAT_INTERVAL = 25000
+
+/**
+ * 拼接聊天 WebSocket 地址。
+ *
+ * 路径是 **`/api/chat/{userId}`**，不是 `/chat/{userId}`：
+ * 生产网关只放行 `/api` 前缀，老路径的握手请求到不了后端（实测 404），
+ * 这正是「生产连不上、本地却正常」的根因。后端同时保留了根路径端点，
+ * 给还没更新的老版本小程序兜底，见 `WebSocketConfig`。
+ */
+export function buildWebSocketUrl(userId) {
+	const url = String(API_BASE_URL || '')
+	if (/^https?:\/\//.test(url)) {
+		return `${url
+			.replace(/^https:/, 'wss:')
+			.replace(/^http:/, 'ws:')
+			.replace(/\/api\/?$/, '')
+			.replace(/\/$/, '')}/api/chat/${userId}`
+	}
+	return `${url.replace(/\/api\/?$/, '')}/api/chat/${userId}`
+}
+
+/**
+ * 给连接挂一个心跳，返回停止函数。
+ *
+ * 只发不收：页面把收到的每条消息都当作流式片段解析，服务端回 pong 反而会被
+ * 拼进正文。心跳的目的只是让「客户端 → 服务端」方向持续有帧，
+ * 顶住 nginx 的 proxy_send_timeout 与各层空闲探测。
+ * 服务端的 `@OnMessage` 收到文本直接丢弃（见 `WebSocketServer.onMessage`）。
+ *
+ * @param {object} socketTask uni.connectSocket 返回的 SocketTask
+ * @returns {() => void} 停止心跳
+ */
+export function attachHeartbeat(socketTask) {
+	if (!socketTask || typeof socketTask.send !== 'function') {
+		return () => undefined
+	}
+	let stopped = false
+	const stop = () => {
+		if (stopped) {
+			return
+		}
+		stopped = true
+		clearInterval(timer)
+	}
+	const timer = setInterval(() => {
+		socketTask.send({
+			data: 'ping',
+			// 连接已经断了：下一次静默失败时顺手把定时器收掉，免得一直空转
+			fail: () => stop()
+		})
+	}, HEARTBEAT_INTERVAL)
+	return stop
+}